A study investigated the age of the Holocene polygonal ice wedge complex in Terrace 1 of the Chara River, plotted an isotope diagram, which allows one to reconstruct winter temperatures of the period ...of ice-wedge formation, and proved the possibility of active formation of ice wedges in the Holocene Optimum in even the southern regions of Siberia. Palynological data indicate only a short-term decrease in summer temperatures relative to current values (under conditions of a slightly more positive summer temperature relative to the current one) in the Chara Depression within the period of 1075 ka BP, whereas the oxygen isotope data on the RIW suggest that winter temperatures were constantly lower than the present-day temperatures.
The conditions of formation of massive ice near the South Tambey gas-condensate field in northern Yamal Peninsula are studied. It is shown that massive ice bodies up to 4.5 m thick occur in the ...Holocene deposits of the high laida and the first terrace. Therefore, they cannot be the remains of glaciers; they are ground ice formations. All three types of massive ice have quite various isotopic compositions: the values of δD range from–107 to–199.7, and δ
18
O from–15.7 to–26.48‰. Such a significant differentiation in isotopic composition is a result of cryogenic fractionation in a freezing water-saturated sediment. The most negative isotope values are even lower in this Holocene massive ice than in the Late Pleistocene ice-wedge ice of Yamal Peninsula.
AMS14C dating and stable isotope plots of Late Pleistocene ice-wedge ice Vasil'chuk, Yurij K; Kim, Jong-Chan; Vasil'chuk, Alla C
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
August 2004, 2004-08-00, Letnik:
223-224
Journal Article
Recenzirano
Strategy for AMS14C dating of organic micro inclusions from syngenetic ice-wedge ice is considered. AMS14C dates are interpreted in terms of fictitious aging of ice-wedge and permafrost sediments due ...to high concentration of allochthonous organic material. The dating of organic material from small sample, gives the reliable 14C age. The 14C dates from syngenetic ice-wedges are compared with the dates of the host sediments surrounding syngenetic ice wedges. AMS14C dating of small samples of ice-wedge ice yields to set δ18O plots from ice-wedges to the time scale and to correlate them with ice core δ18O record.
The origin of the massive ice is important for understanding the Quaternary history of the Yamal region and to predict the occurrence of massive ice, which is important for gas exploration and the ...development of infrastructure. Massive ice bodies occur in the Bovanenkovo gas field area within sediments such as layers, laccoliths, rods and lenses. Maximal thickness of the tabular ice is 28,5 m; mean thickness is about 8 m. Deposits of the third terrace underlying and overlapping the tabular ice had been formed from 25 ka BP to 20 ka BP, according to 14C dates. Oxygen-isotope values (δ18О) of massive ices are ranged from 12, 49‰ up to -22, 95‰. Deuterium (δD) values vary from -91, 7‰ up to -177, 1‰. Deuterium excess (dexc) changes from 3, 4 to 10, 6‰. Both homogenous and contrast distribution δ18О and (δD) vs. depths in massive ice bodies evidences the segregated and/or infiltrated-segregated manner of ice formation. Pollen, spores and algae spectra from ice are similar to pollen characteristics of modern lacustrine and coastal floodplain sediments in the area. The ingression of cold seawaters on a coastal flood plain caused freezing and ice segregation, with the formation of extensive ice layers under the large but shallow lakes. As a result, syngenetic and genetically heterogeneous ice, such as: segregated, infiltrated-segregated, lake bottom congelation ice etc. was formed.
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